Preparation of electrocatalytically active chitosan biopolymer films by solvent-dependant electrophoretic deposition

Abstract

Herein, it has been shown that electrocatalytically active films of the biopolymer chitosan could be electrophoretically deposited from strong acid (HCl) medium and could be used for the mediatorless electrocatalytic oxidation of nicotinamide adenine dinucleotide (NADH) at neutral pH. The chitosan-modified electrode alleviated electrode fouling effects and decreased NADH oxidation overpotential by ~540 mV. Sensitivity and detection limit were found to be 1.049 μA µM−1 and 0.017 µM, respectively. The modified electrode exhibited a linear dynamic range between 39.8 × 10−6 and 23.4 × 10−5 M. The morphology of the electrochemically deposited chitosan films from solvents such as HCl and acetic acid was analyzed in detail using scanning electron microscopy. It was shown by zeta potential measurements that the chitosan molecules were stabilized to a greater extent in the presence of p-toluene sulfonic acid in HCl medium and led to a well-defined amperometric response for NADH oxidation. The proof of concept for ethanol sensing was demonstrated by coupling alcohol dehydrogenase enzyme to the chitosan-modified electrode using NADH transduction.